1. Field of the Invention
The invention relates to an optical device. Particularly, the invention relates to a projection apparatus.
2. Description of Related Art
A projection apparatus is a display apparatus used for producing large size images. An imaging principle of the projection apparatus is to convert a light beam generated by a light source into an image beam through a light valve, and then converts the image beam into a projection beam through a projection lens, and projects the projection beam onto a screen or a wall. With development of the projection technique and reduction of fabrication cost, utilization of the projection apparatus is gradually developed from commercial use to domestic use.
Along with increasing demands in carbon reduction and green energy, in the projection apparatus, a solid state illumination (SSI) is gradually used to replace a conventional high pressure mercury lamp, the solid state light source is, for example, a light-emitting diode (LED) light source or a laser diode light source. Generally, a blu-ray solid state light source, a green-ray solid state light source and a red-ray solid state light source are configured in the projection device, and since the temperature may greatly influence a lighting efficiency of the solid state light source, a plurality of fans are generally disposed near the solid state light sources for directly providing heat dissipation airflows to the solid state light sources. However, such design leads to a higher production cost due to relatively more fans, and leads to a larger size of the projection apparatus. Moreover, according to the above configuration, the fans are generally disposed at an air inlet of the projection apparatus, i.e. an upstream of a flow field of the heat dissipation airflow in internal of the projection apparatus, so that it is uneasy to control a flow field direction of the heat dissipation airflow, which is liable to cause a flow field chaos and cause a high temperature of the devices at a downstream of the system flow field.
In U.S. Publication No. 20110181842, an LED light source is disposed between two fans. In U.S. Publication No. 20100110393, a fan is disposed aside an LED light source. U.S. Publication No. 20080252858 discloses a projection apparatus, in which a fan is disposed at a side of a lamp module. In U.S. Publication No. 20030043584, a fan is disposed at a side of a lamp module. U.S. Publication No. 20090207382 discloses a projection system, in which an airflow generated by a fan is used to guide and exhaust the heat generated by an optical module. U.S. Pat. No. 7,144,118 discloses a projection apparatus having an air inlet and a fan, in which the fan is used to guide external air into the projector to flow through heating elements. However, heat dissipation effects of the aforementioned patents are still limited.